Rosalynn
Chemical
- Feb 19, 2003
- 28
I'm troubleshooting an existing operating facility.
We have excessive pressure drop between two parallel oil/water separation vessels and the inlet to the "Sales Oil Cooler" about 200 ft. downstream. The vessels are the third ones in line to receive heavy oil production from the wells in the field.
I've calculated the pressure drop through the control valves (one on the exit of each vessel) and through the piping. The piping is simple: lines off each vessel with gate valves to isolate the control valves, joining at a tee and travelling to the heat exchanger. There are the typical ups, downs, and elbows you'd expect, but nothing complicated. (There are two branch lines, but they are isolated and there is no flow through them.) Yet the pressure drop is 300 kPa instead of 100 kPa (45 psi vs. 15 psi). It is limiting throughput and therefore limiting profits.
I've gone over and over this system. I think my calculations are correct (I've used Fisher Firstvue for the control valves, Hysis and nomographs for the piping effective length and pressure drop). Perhaps I'm too close to see the obvious? I'd welcome your ideas on what to check. Xray the piping for restrictions? Sand in low points? Online cleaning options? There is only one intermediate location for a gauge to be installed--I'll get that done asap and see if it can narrow things down. Since I have two vessels, two flow meters and two control valves in parallel which say the same thing, I'm thinking that they are reading correctly. (The flows are also consistent with other meter readings in the plant.) The gauge at the exchanger is new, and its reading is corroborated by gauges downstream.
Thanks.
We have excessive pressure drop between two parallel oil/water separation vessels and the inlet to the "Sales Oil Cooler" about 200 ft. downstream. The vessels are the third ones in line to receive heavy oil production from the wells in the field.
I've calculated the pressure drop through the control valves (one on the exit of each vessel) and through the piping. The piping is simple: lines off each vessel with gate valves to isolate the control valves, joining at a tee and travelling to the heat exchanger. There are the typical ups, downs, and elbows you'd expect, but nothing complicated. (There are two branch lines, but they are isolated and there is no flow through them.) Yet the pressure drop is 300 kPa instead of 100 kPa (45 psi vs. 15 psi). It is limiting throughput and therefore limiting profits.
I've gone over and over this system. I think my calculations are correct (I've used Fisher Firstvue for the control valves, Hysis and nomographs for the piping effective length and pressure drop). Perhaps I'm too close to see the obvious? I'd welcome your ideas on what to check. Xray the piping for restrictions? Sand in low points? Online cleaning options? There is only one intermediate location for a gauge to be installed--I'll get that done asap and see if it can narrow things down. Since I have two vessels, two flow meters and two control valves in parallel which say the same thing, I'm thinking that they are reading correctly. (The flows are also consistent with other meter readings in the plant.) The gauge at the exchanger is new, and its reading is corroborated by gauges downstream.
Thanks.
